Control of heart rate

• Autonomic- a division of the motor nervous system which carries nerve impulses to glands, smooth and cardiac muscle and is not under voluntary control.
• AV node- a second group of cells which lies between the atria. After a short delay , it conveys a wave of electrical excitation between the ventricles along the purkinje tissues.
• Bundle of His- the structure that is made of the purkinje fibers that conducts the wave through the atrioventricular septum to the base of the ventricles.
• Cardiac muscle- found exclusively in the heart (not under conscious control).
• CNS- the brain and spinal cord
• Medulla oblongata- Region of the brain which controls the heart rate. it has two centers- one which increases heart rate that is linked to the SAN by the sympathetic NS and one which decreases heart rate that is linked to the SAN by the parasympathetic NS.
• Myogenic- contraction is initiated from within the muscles itself rather than by nervous impulse from outside.
• Peripheral nervous system- Pairs of nerves that originate from either the brain or spinal cord to the rest of the body. Divided into the sensory and motor nervous system.
• The somatic system controls conscious activity , the autonomic controls subconscious activities.
• Heartbeat:

  1. An action potential is initiated by the sinoatrial node which is in the wall of the right atrium.
  2. the action potential causes an impulse to travel through walls of the atria to the AV node
  3. the AV node triggers a wave of electrical activity which travels down the purkyne fibres in the bundle of his.
  4. the heart muscles contract from the base upwards , squeezing the ventricles and pushing blood out at high pressure through the pulmonary artery and the aorta.